The WSIT Tutorial

How Security Policy Works

The WSIT Web Service Security Policy implementation builds on the features provided by the Web Service Policy implementation in WSIT. It enables users to use XML elements to specify the security requirements of a web service endpoint, that is, how messages are secured on the communication path between the client and the web service. The web service endpoint specifies the security requirements to the client as assertions (see Figure 2–9).

Figure 2–9 Security Policy Exchange

Diagram of security policy exchange

The security policy model uses the policy specified in the WSDL file for associating policy assertions with web service communication. As a result, whenever possible, the security policy assertions do not use parameters or attributes. This enables first-level, QName-based assertion matching to be done at the framework level without security domain-specific knowledge. The first-level matching provides a narrowed set of policy alternatives that are shared by the client and web service endpoint when they attempt to establish a secure communication path.

Note –

A QName is a qualified name, as specified by the XML Schema Part2: Datatypes specification, Namespaces in XML, and Namespaces in XML Errata. A qualified name is made up of a namespace URI, a local part, and a prefix.

The benefit of representing security requirements as assertions is that QName matching is sufficient to find common security alternatives and that many aspects of security can be factored out and reused. For example, it may be common that the security mechanism is constant for a web service endpoint, but that the message parts that are protected, or secured, may vary by message action.

The following types of assertions are supported: